1. Field of the Invention
The present invention relates to the field of scanning microscopy. More particularly, the invention concerns the non-intrusive magnetic imaging of devices and systems that generate and/or sense magnetic fields, including the magnetic field output of magnetic write heads and the magnetic response of magnetic read heads.
2. Description of the Prior Art
By the way of background, current methods for magnetic imaging suffer from various limitations. The most widespread method is Magnetic Force Microscopy (MFM). Even though MFM provides high spatial resolution, it does not actually measure magnetic field, but rather the magnetic field gradient, making interpretation of the images difficult and, in some cases, impossible to de-convolute. Additionally, MFM only works with static magnetic fields and has no time-domain capabilities. Another wide-spread magnetic imaging method is Kerr microscopy, which does provide time-resolved magnetic field imaging. However, Kerr microscopy can only image magnetization of the material, thus limiting the technique in the choice of materials. Additionally, because Kerr microscopy is an optical technique, the spatial resolution is limited by the wavelength of light. More recent advances in the field of magnetic imaging, such as Lorenz microscopy, ballistic electron emission microscopy, and polarization X-ray microscopy also suffer from various limitations, and are complicated and expensive.
Accordingly, a need exists for a new technique for magnetic imaging that can provide unambiguous magnetic field mapping with high spatial resolution, and which also preferably provides time-domain capabilities. One area where such a technique could be immediately utilized is the characterization of magnetic recording heads. Although a variety of characterization techniques have been developed in this area, they involve characterization of a more complicated system, which includes not only the head for magnetic recording, but also the magnetic recording media and the electronics for operating the head. In addition to being an indirect method of head characterization, these methods involve long evaluation cycles and the high cost associated with building individual sliders.
What is therefore required is a magnetic imaging system that allows non-intrusive imaging of magnetic fields with high (e.g., ˜1–10 nm) spatial resolution and high (e.g. ˜1 nsec or better) temporal resolution, and whose functions include imaging the time-resolved magnetic field output of a magnetic write head and imaging the magnetic response of a magnetic read head.